Phone numbers in Rio, Illinois
Rio has 3 phone prefixes in area code 309.
Biggest holders: Stratus Networks, Frontier, Oneida Network Services. This is the local calling area (rate center) where those prefixes were first assigned.
- Local phone company 33%
- Phone company 67%
Every prefix in Rio
Search the first six digits of a number in this list. If it's here, the number started in Rio with the carrier shown. If it isn't, check the Illinois page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 309-805 | Stratus Networks | Phone company | 2020 |
| 309-872 | Frontier | Local phone company | – |
| 309-972 | Oneida Network Services | Phone company | – |
Most prefixes are pooled: the 10,000 numbers in each are handed out in blocks of 1,000 to different carriers, and people can also take their numbers to another carrier. So the carrier shown is where the prefix started, not a guarantee about any one number. Source: NANPA central office code records, 2026-10-10.